Floodplain Restoration Monitoring on the Napa River

The USACE and Napa County Flood Control and Water Conservation District implemented the Napa River Flood Protection Project in 2000. The Project aimed to achieve 100-year level flood protection by reconnecting Napa River to its historical floodplain, provide flood damage benefits that exceed Project costs, and mitigate Project impacts on fish and wildlife by restoring wetlands throughout the floodplain. The Project converted previously diked agricultural baylands to a mosaic of tidally influenced wetlands and uplands creating important wildlife and bird habitat. The 40-year vegetation monitoring plan, with 5-year monitoring intervals, was established to ensure restoration goals are met.

Stillwater completed vegetation monitoring in 2012 (year 10) and 2017 (year 15). Stillwater acquired high resolution aerial imagery using a quadcopter unmanned aircraft system (UAS or drone) in spring 2017, which was used to update the habitat map in GIS. Ground-control points were surveyed and imagery was processed using Pix4Dmapper Pro to create an orthorectified photo-mosaic. The UAS allowed Stillwater to collect recent imagery at a low tidal stage, resulting in a more complete and accurate vegetation map to track habitat restoration progress. Vegetation data was also gathered at 15 transects and 182 plots over the 1,233 ac Project area. The Project has already met the 40-year acreage goals for five of seven restored habitats (tidal mudflats, seasonal emergent wetlands, shaded riverine aquatic, riparian forest/scrub shrub, and grasslands), and is adaptively managing the brackish emergent marsh and high-value oak woodlands to ensure they are on track to meet restoration goals.
 

Overview

Location: Napa River, Napa County, California

Clients:  Napa County Flood Control and Water Conservation District

Project Manager: Megan Keever

Project Lead(s)

Megan Keever
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Work Products

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2017 Vegetation Monitoring Report, Napa River Flood Protection Project
Poster, Habitat development on the Napa River: Restoration Progress

IMAGE

A quadcopter drone was used to capture aerial imagery for habitat mapping and vegetation typing. This photo shows the southern end of the site where brackish emergent marsh species are colonizing the open mud flats.

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